def test_dequeue_when_empty():
# TODO it should raise an exception when dequeueing an empty queue
q = Queue()
with pytest.raises(InvalidOperationError) as e:
q.dequeue()
assert str(e.value) == "Method not allowed on empty collection"
def test_dequeue():
q = Queue()
q.enqueue('apple')
q.dequeue()
actual = q.is_empty()
expected = True
assert actual == expected
def test_can_empty_queue():
queue = Queue()
queue.enqueue(1)
queue.enqueue(1)
queue.dequeue()
queue.dequeue()
actual = queue.is_empty()
expected = True
assert actual == expected
def test_exhausted():
# TODO TODO is empty should return true after dequeueing all previously queued items
q = Queue()
q.enqueue('apples')
q.enqueue('oranges')
q.dequeue()
q.dequeue()
actual = q.is_empty()
expected = True
assert actual == expected
def test_queue_dequeue_until_empty():
value1 = 1
value2 = 2
queue = Queue()
queue.enqueue(value1)
queue.enqueue(value2)
queue.dequeue()
queue.dequeue()
actual = queue.front
expected = None
assert actual == expected
def test_peek_post_dequeue():
# TODO it should return a new first value if peek is called after a dequeue
q = Queue()
q.enqueue('apples')
q.enqueue('oranges')
actual = q.peek()
expected = 'apples'
assert actual == expected
q.dequeue()
actual = q.peek()
expected = 'oranges'
assert actual == expected
class AnimalShelter:
def __init__(self):
self.cats = Queue()
self.dogs = Queue()
self.animal_order = Queue()
def enqueue(self, animal):
"""Add passed in animal object to the queue
Args:
animal (obj): Expects either Cat() or Dog() instance
Raises:
ValueError: If not Cat() or Dog() is passed in
"""
if animal.type == 'Cat':
self.cats.enqueue(animal)
self.animal_order.enqueue('Cat')
elif animal.type == 'Dog':
self.dogs.enqueue(animal)
self.animal_order.enqueue('Dog')
else:
raise ValueError('Must be either a cat or a dog!')
def dequeue(self, preference=None):
"""Get the longest waiting in queue Cat() or Dog() depending on passed in preference. If no preference passed in get the longest waiting in queue animal
Args:
preference (str, optional): Animal to be returned (cat or dog). Defaults to None.
Raises:
ValueError: If not a cat or a dog is passed in as a preference
AttributeError: When no animals is available
Returns:
obj: Cat() or Dog() instance
"""
try:
if not preference:
preference = self.animal_order.dequeue()
if preference.lower() == 'cat':
animal = self.cats.dequeue()
elif preference.lower() == 'dog':
animal = self.dogs.dequeue()
else:
raise ValueError('Must be either a cat or a dog!')
return animal
except AttributeError as err:
raise AttributeError('No animals available!')
def test_dequeue_when_full():
q = Queue()
q.enqueue("apples")
q.enqueue("bananas")
actual = q.dequeue()
expected = "apples"
assert actual == expected
def test_dequeue_one():
queue = Queue()
queue.enqueue(2)
queue.enqueue(1)
actual = queue.dequeue()
expected = 2
assert actual == expected
def test_queue_dequeue():
value = 1
queue = Queue()
queue.enqueue(value)
actual = queue.dequeue()
expected = value
assert actual == expected
def add(self, val: any) -> None:
"""Add a new node with Breadth first approach
Args:
val (any): Value to add
"""
new_node = Node(val)
if self.root:
q = Queue()
q.enqueue(self.root)
while not q.is_empty():
node = q.dequeue()
if node.left:
q.enqueue(node.left)
else:
node.left = new_node
return
if node.right:
q.enqueue(node.right)
else:
node.right = new_node
return
else:
self.root = new_node
def breadth_first(self, start: Vertex) -> set:
"""Traverse a graph in breadth-first manner and return a set of Vertices
Args:
start (Vertex): Starting point of the traversal
Raises:
KeyError: If provided vertex is not part of the graph
Returns:
set: Set of vertices
"""
q = Queue()
output = set()
if not start in self.adjacency_list:
raise KeyError('Given Vertex is not part of the Graph')
q.enqueue(start)
while not q.is_empty():
vertex = q.dequeue()
output.add(vertex)
for neighbor in self.get_neighbors(vertex):
if neighbor['vertex'] not in output:
q.enqueue(neighbor['vertex'])
return output
def breadth_first(self, vertex):
node = []
breadth = Queue()
breadth.enqueue(vertex)
visited = set()
while not breadth.is_empty():
front = breadth.dequeue()
node.append(front.value)
for neighbor in self.get_neighbor(front):
if neighbor.vertex.value not in visited:
visited.add(neighbor.vertex.value)
breadth.enqueue(neighbor.vertex)
return node
def breadth_first(self) -> list:
"""Traverse the tree in breadth-first manner
Returns:
list: Values of the tree
"""
output = []
if self.root:
q = Queue()
q.enqueue(self.root)
while not q.is_empty():
el = q.dequeue()
output.append(el.val)
if el.left:
q.enqueue(el.left)
if el.right:
q.enqueue(el.right)
return output
def test_queue_dequeue_empty_exception():
queue = Queue()
with pytest.raises(Exception):
queue.dequeue()